Unanswered Gearing questions

[frogcity]

I have a 2017 HPC trailblazer 9 speed sram with the Bafang BBSHD motor. It is time for me to replace the chainring and cassette. It has a 42 tooth chainring and an 11-36 cassette. This gives me gear ratios from 3.818 to 1.1666. If I change to a 44 chainring and an 11-40 cassette, this will give me gear ratios from 4 to 1.1. This will give me a wider range of ratios. A 46 chainring and the same 11-40 cassette would give me ratios from 4.18 to 1.15. Only a bit better low end ratio and quite a bit more than the original setup. I am leaning towards the second option. What disadvantages or issues would this create over the original setup?.

 

[BeBiker]

- check if your derailleur is compatible with your plans. Most have it in the specs, my 10sp with sg cage works until 11-46t
- if your derailleur doesn't allow this, you can use a derailleur hanger, with the risk of a bit less precise shifting the smallest cogs.
- a wider spread is only a disadvantage without electricity, on an Emtb not an issue.
- my newest bike is a 12sp, but most of the time I shift +2 or -2, so your 9sp will work ok.

Your choice between 42t, 44t, 46t is mostly dependent of the terrain you ride, and the folks you ride with.
The frame of my 10sp accepts until 42t.
I tried 36t, 38t, 40t and 42t, actually the 38t seems the best compromise between climb and topspeed.